Let \(a, b, c, d, e, f\) be nonnegative real numbers.
(a) Prove that
\((a^2 + b^2)^2 (c^4 + d^4)(e^4 + f^4) \ge (ace + bdf)^4.\)
(b) Prove that
\((a^2 + b^2)(c^2 + d^2)(e^2 + f^2) \ge (ace + bdf)^2.\)
This is easy if you use Cauchy-Schwarz.
So why don't you show us how easy it is and aprove one of them.
Attn: Guest aske
What have you done towards answering?
Have you done any of the expansions?